Heather Locklear -- Surveillance Video

Law enforcement sources tell TMZ Heather Locklear's swanky neighborhood security system is what led deputies to her doorstep last Saturday ... which then led to her arrest for hit-and-run ... but there may be a big problem fingering Heather as the driver.

Sources say police checked the surveillance footage from the guard shack at her Westlake Village neighborhood sometime after her alleged crash ... and saw footage of Heather driving her black BMW into the complex ... and the BMW had damage in the right wheel well area consistent with the accident scene.

But here's the hole in the case. The video was recorded many hours after the accident ... so even if there's clear proof Heather's car was in the accident at 4 AM Saturday, there is no smoking gun placing her behind the wheel at that time.

Cops also collected debris from the crash scene -- which matched up with Locklear's damaged ride ... but still, there's no clear proof Heather was the driver.